2019 CX-5 2.5T Misfire

[FrozenApple]

I updated the thread as i go, so please scroll through the pages as i have provided updates as i go.


Here is to my first post, i thought this might be useful to some people in the future.

Before i dive into the details a few details regarding to the vehicle.
Vehicle was purchased Jan 2019
Currently 24090kms
Synthetic 5W30 Oil Change every 5000km or 6 month whichever comes first.

Initially I noticed a slight lump when idling sometimes, but it is not bad at all, you do notice it with your foot on the pedal and you do feel it, but i mean its so slight its barely noticable, no power loss during acceleration or cuising, no check engine light, no difference in terms of fuel economy. Now this has been going on for at least 2 month.

A week ago my check engine light turned on, and i thought its because i didt fully tighten the gas cap because i did fill up a day ago, few days passed check engine light is still there, so i decided to pull code to see.

interesting stuff i found with my cheap scan tool, i was shocked to see how many module this tool picked up.

This would make any future diagnostic easier, now back to the problem at hand.

As you can see misfire cyl3, I was curious on how bad the misfire was, so i cleared the dtc and the code did not come back, I checked the datalist for misfire count and surely you can see the misfire count go up slowly, but obviously it is not severe enough to set the check engine light.
A regular person prob would not even notice the tiny vibration, and because its not 100% misfire and it is not severe, it does not set the check engine light, but with a scan tool you can see the misfire count go up slowly as you idle.

some interesting data point i saw while going through the list, it has a counter for how much energy the engine produced, i also see a data point for engine sound enhancement, thats a weird one for me, the number does change as you drive and the car measures engine oil level in mm.

OK, anyways back to the issue at hand, the misfire is very interesting, the count would only go up when idling, during acceleration or hard acceleration there is 0 misfire count, it does not matter if car is cold or hot.

Initially i was going to swap the coils, but i assume it can not be，if coil is bad it would misfire at idle and acceleration and especially hard acceleration and same with spark plugs, i then thought perhaps the injector might have problem but it wouldnt make any sense to only misfire at idling.

I made an appointment with mazda, and will update the thread as i go, but it is a very interesting problem with the 2.5T engine so i thought i share with everyone.

 

[erhayes]

Keep us informed. Ed

 

[Unobtanium]

I had a rough idle once. Car ran 100% under ANY throttle, and it started st a stop light after 30mi of driving. Transmission shifter position and ac on or off had zero effect. I stopped and restarted the car and it was fine. It felt like a sticky IAC on an older vehicle exactly.

I just changed the plugs a week ago at the 40k mile mark and they looked fine, minus some burned brown around the ceramic insulators furthest from the coil.

 

[FrozenApple]

I had a rough idle once. Car ran 100% under ANY throttle, and it started st a stop light after 30mi of driving. Transmission shifter position and ac on or off had zero effect. I stopped and restarted the car and it was fine. It felt like a sticky IAC on an older vehicle exactly.

I just changed the plugs a week ago at the 40k mile mark and they looked fine, minus some burned brown around the ceramic insulators furthest from the coil.

interesting, for mine it does not matter when its cold start or hot, it will misfire only when idling in gear or not, but under acceleration or cuising at any speed it is good, confirmed no misfire count with scantool

 

[Chris_Top_Her]

Eh, whenever I get a misfire, It's always been new plug time. I already run 93 always anyways don't put cheap fuel in the tank, and often run fuel additives. Usually I'll add something strong like G2P anyways before I buy new plugs since I buy OEM, but historically my misfires simply mean time for new plugs. That's typically the end of the problem. And no, you can't look at a plug and be able to tell if the electrode is good or not unless it's obviously damaged (how can you tell if the microns thick plating is suitable or not lol). You need an ohm meter to do so. But I maintain my engine as such other common factors of a misfire are highly unlikely (dirty fuel injector, dirty PCV system or dirty valve problem etc).

Assuming fuel system/vacuum system gets maintenance, you could reset the fuel trim by unplugging the battery, but typically if this was the problem you would have a rich/lean code. Maybe you just got bad gas, that happened to me in Atlanta a few times while I was visiting.

 

[FrozenApple]

Eh, whenever I get a misfire, It's always been new plug time. I already run 93 always anyways don't put cheap fuel in the tank, and often run fuel additives. Usually I'll add something strong like G2P anyways before I buy new plugs since I buy OEM, but historically my misfires simply mean time for new plugs. That's typically the end of the problem. And no, you can't look at a plug and be able to tell if the electrode is good or not unless it's obviously damaged (how can you tell if the microns thick plating is suitable or not lol). You need an ohm meter to do so. But I maintain my engine as such other common factors of a misfire are highly unlikely (dirty fuel injector, dirty PCV system or dirty valve problem etc).

Assuming fuel system/vacuum system gets maintenance, you could reset the fuel trim by unplugging the battery, but typically if this was the problem you would have a rich/lean code. Maybe you just got bad gas, that happened to me in Atlanta a few times while I was visiting.

Its very rare for plug replacement at 24000km no? the newer skyactiv calls for spark plug at early 50000km.
I always put in 91 ever since i bought the car. Maybe it is coil problem, lets see what dealership will say when i take the car in, hopefully they dont just brush me off telling me to monitor the situation, in that case ill prob swap the coils and see if the misfire transfers

 

[yrwei52]

Its very rare for plug replacement at 24000km no? the newer skyactiv calls for spark plug at early 50000km.
I always put in 91 ever since i bought the car. Maybe it is coil problem, lets see what dealership will say when i take the car in, hopefully they dont just brush me off telling me to monitor the situation, in that case ill prob swap the coils and see if the misfire transfers

I agree with Chris_Top_Her, more than likely you have a mediocre spark plug on cylinder #3. Next possibility is you have a mediocre coil pack on cylinder #3. Please keep us updated after your dealer visit.

 

[AVC]

Should be a freeze frame record associated with the P0303. Can you post that?

And also post more complete data idling in park? (MAF, MAP, long and short fuel trims %load...)

 

[AVC]

The OP already Disappeared?

 

[FrozenApple]

The OP already Disappeared?

i apologize for late response, here it is.

 

[AVC]

Maybe I missed it; is this a CX-5? Protege? Model Year?

From the freeze frame, the trims a slightly positive, but still in closed loop. I'd look closely at coil pack #3, swap it with #4. Posisbly a bad plug, but I'd expect drivability stumbles and climbing miss counts, especially low speed medium to high throttle.

 

[FrozenApple]

Maybe I missed it; is this a CX-5? Protege? Model Year?

From the freeze frame, the trims a slightly positive, but still in closed loop. I'd look closely at coil pack #3, swap it with #4. Posisbly a bad plug, but I'd expect drivability stumbles and climbing miss counts, especially low speed medium to high throttle.

This is a 2019 Cx-5, the misfire is only there when idling, while driving no misfire count. Do u work for an mazda dealership? if u dont mind me asking

 

[FrozenApple]

Update:

Took the car in to mazda dealership today, after dropping the car off for 2 hours got a call back.

-Advisor told me they found misfire on cyl3, and no they can not reproduce it.
-Told me to monitor the situation
-Recommend carbon cleaning service which i denied

I told the advisor that the vehicle would only misfire when idling, and if they would check the datalist they will see it, the advisor told me they checked the datalist and they did not see any (thats full of bs). I then requested if they can at least swap the coils, and he says they did swap #3 with #2.

After getting vehicle back, i noticed the misfire is still there of course, tried to plug in scan tool to see datalist to confirm if its still #3 cyl misfire, scantool can no longer connect to vehicle, this is when i realize they performed a pcm update. Now there is no way for me to check the datalist, i can only read dtc once its set, and the generic datalist does not contain misfire monitor count.

I took 2 pictures of the coils and the bracket on top of the coils, notice how the manufacture mark some bolt with marker and surprisingly the mark is exactly where it was, obviously the bracket needed to be moved, or removed for cyl #3 and #2 to come out its almost like the bolt is untouched, so..ill let u be the judge, did they indeed swap the coils? or is it just bulls***?

 

[GTEyes]

Update:

Took the car in to mazda dealership today, after dropping the car off for 2 hours got a call back.

-Advisor told me they found misfire on cyl3, and no they can not reproduce it.
-Told me to monitor the situation
-Recommend carbon cleaning service which i denied

I told the advisor that the vehicle would only misfire when idling, and if they would check the datalist they will see it, the advisor told me they checked the datalist and they did not see any (thats full of bs). I then requested if they can at least swap the coils, and he says they did swap #3 with #2.

After getting vehicle back, i noticed the misfire is still there of course, tried to plug in scan tool to see datalist to confirm if its still #3 cyl misfire, scantool can no longer connect to vehicle, this is when i realize they performed a pcm update. Now there is no way for me to check the datalist, i can only read dtc once its set, and the generic datalist does not contain misfire monitor count.

I took 2 pictures of the coils and the bracket on top of the coils, notice how the manufacture mark some bolt with marker and surprisingly the mark is exactly where it was, obviously the bracket needed to be moved, or removed for cyl #3 and #2 to come out its almost like the bolt is untouched, so..ill let u be the judge, did they indeed swap the coils? or is it just bulls***?

I had this same issue on my 2018 mazda6 turbo. They did the decarb on it; it did not fix the issue. They replaced spark plugs, no fix. They tried a few other fixes but nothing fixed the issue. Final test was a compression test which they found one cylinder was significantly lower than the others.

I was able to reproduce the rough running by having the car warmed up, engaged the emergency brake and placing the car in "drive" and no foot on the brake. The load of the car in gear with the emergency brake on caused the misfire to happen and the car would run rough. I was able to document it with video, I couldn't believe how much the engine was bouncing and vibrating.

It felt like the car was going to stall although it never did. I drove the car months like this before I decided something was seriously wrong and thankfully I got a check engine light with a misfire code.

There was a very obvious bounce/unbalance occurring in the engine. The whole car would bounce...I noticed it the most when in traffic and slowly letting foot off the brake, you could tell the engine wasn't running right and the whole car would do this bounce/oscillation sensation. Here's a video of the bouncing with a bottle of soda in the cup holder,

They ended up replacing my engine. The compression was down considerably in one of the cylinders. I recommend you get them to do a compression test on your engine.

Here is the thread on it,

2018 Signature - MIL - Misfire cylinder#2

www.mazda6club.com

My new engine runs butter smooth and doesn't suffer from the occasional hard starts, rough starts and rough idle when in traffic. I also didn't realize how loud my old engine was when cold started..new engine is dramatically more quiet.

Best of luck with the issue. I had my car back to the dealer a handful of times before I declared it was a safety issue and left it at the dealership. They were kind enough to put me in a rental.

 

[FrozenApple]

I had this same issue on my 2018 mazda6 turbo. They did the decarb on it; it did not fix the issue. They replaced spark plugs, no fix. They tried a few other fixes but nothing fixed the issue. Final test was a compression test which they found one cylinder was significantly lower than the others.

I was able to reproduce the rough running by having the car warmed up, engaged the emergency brake and placing the car in "drive" and no foot on the brake. The load of the car in gear with the emergency brake on caused the misfire to happen and the car would run rough. I was able to document it with video, I couldn't believe how much the engine was bouncing and vibrating.

It felt like the car was going to stall although it never did. I drove the car months like this before I decided something was seriously wrong and thankfully I got a check engine light with a misfire code.

There was a very obvious bounce/unbalance occurring in the engine. The whole car would bounce...I noticed it the most when in traffic and slowly letting foot off the brake, you could tell the engine wasn't running right and the whole car would do this bounce/oscillation sensation. Here's a video of the bouncing with a bottle of soda in the cup holder,

They ended up replacing my engine. The compression was down considerably in one of the cylinders. I recommend you get them to do a compression test on your engine.

Here is the thread on it,

2018 Signature - MIL - Misfire cylinder#2

www.mazda6club.com

My new engine runs butter smooth and doesn't suffer from the occasional hard starts, rough starts and rough idle when in traffic. I also didn't realize how loud my old engine was when cold started..new engine is dramatically more quiet.

Best of luck with the issue. I had my car back to the dealer a handful of times before I declared it was a safety issue and left it at the dealership. They were kind enough to put me in a rental.

oh yea i was actually reading your post prior to making this one, i certainly hope its not an engine issue, but this stupid dealership is so lazy, they only updated the pcm software and did not even look in details, so pretty much i either have to pull the plugs myself or wait for cel to turn back on.

Thank you for your insight on this issue tho, i do notice more vibration when engage in reverse with parking brake on.

 

[GTEyes]

oh yea i was actually reading your post prior to making this one, i certainly hope its not an engine issue, but this stupid dealership is so lazy, they only updated the pcm software and did not even look in details, so pretty much i either have to pull the plugs myself or wait for cel to turn back on.

From what you've described, it sounds so similar to what my car was doing.

I found my CEL would come on when I was driving around town, stop and go, running errands, etc... it never came on when I was on the highway (95% of my driving) or when it was actually idling rough...

 

[FrozenApple]

From what you've described, it sounds so similar to what my car was doing.

I found my CEL would come on when I was driving around town, stop and go, running errands, etc... it never came on when I was on the highway (95% of my driving) or when it was actually idling rough...

Because i had access to a scan tool that could read misfire count, i was able to see when it was misfiring, for mine when driving its 0 misfire count, but right when u start idling the count would just climb up.

for my cel it would only illuminate if im idling, and currently it is not severe enough to turn the check engine light on consistantly, it would turn on sometimes idling if it misfires badly for a brief moment

 

[AVC]

This is a 2019 Cx-5, the misfire is only there when idling, while driving no misfire count. Do u work for an mazda dealership? if u dont mind me asking

No just a DIY with 40 years of my own troubleshooting and wrenching. A PCM update should NOT prevent a OBD compliant scan tool from connecting; by law any compliant scan tool must be able to read basic Mode 1,2,3,5,6 data.

As soon as you get another string of provable misfires, withe CEL on, you'll have a reason for them to look at it again. If you believe they didn't actually swap the coils, then press them on it. If the coil or plug isn't the cause, then press them to do a relative compression check, which they can do in 10 minutes with a DC amp clamp, a scope and removing the low pressure fuel pump relay. The relative compression check is typically the last thing I'd suspect and perform on a such a low mileage car.

On many cars--Mazdas?-- you can do an video/audio recording of cranking in clear flood mode (accelerator floored and cranking). It's pretty easy to tell from the audio whether there is a significantly low compression cylander.

 

[AVC]

Also, you can download (Windows) or cellphone app of Forscan, and use it with a bluetooth or USB OBD adapter (what I do). Forscan isn't as user friendly as Torque, but it reads all sorts of basic and advanced PID's, including misfire counters. With the PC version + $25 USB OBD adapter, mine reads 250+ PIDS/sec.

 

[AVC]

BTW, we can tell your engine is not U.S.--the oil cap is marked 5W-30.